This invention relates to valves and more particularly to rotary flow control valves.
A rotary flow control valve typically includes a valve body, a passage formed in the valve body for a through flow of a fluid, a valve spool mounted for rotation in the valve body and including a transverse port movable upon rotation of the spool between an open position in which it is aligned with the passage to allow flow through the passage and a closed position in which it is transverse of the passage and the passage is blocked, and means for rotating the spool so as to move the port between its open and closed positions. Various mechanisms have been proposed to rotate the valve spool to accomplish the valving function. Whereas these rotating mechanisms have been generally satisfactory, they have suffered from one or more disadvantages. Specifically, they have been unduly complicated in construction; they have been overly expensive to manufacture; they have not provided a precise valving action; they have required considerable maintenance; they have been relatively short lived especially in hostile environments; they have required a complicated installation procedure with respect to any given hydraulic system in which the valve is being incorporated; or they have required a complicated external piping system to provide the power to achieve the valving function.